1. Technical Field
The present invention relates to a motor control device that controls a rotation direction of a motor through actuation of a switch.
2. Related Art
In order to adjust orientations of mirror sides of outer mirrors which are provided on left and right doors of an automobile, respectively, in a vertical direction and/or a horizontal direction, for example, there has been used an electrically-driven and remote-controlled switch including an operation knob capable of tilting in four directions. Japanese Unexamined Patent Publication No. 2001-351477 and Japanese Utility Model Registration No. 2590446 disclose switches of this type, respectively.
In Japanese Unexamined Patent Publication No. 2001-351477, an operation knob has a protrusion formed at a center of a back side thereof and a switch body includes a normally-closed shutoff switch provided at a portion corresponding to the protrusion. In a case where a user actuates the operation knob in all directions concurrently (concurrent actuation), the protrusion formed on the back side of the operation knob presses the shutoff switch to prevent a dead short in such a manner that the shutoff switch interrupts an electric current between circuits on a wiring board (see FIG. 3). As a conventional technique of preventing such a dead short in the case of occurrence of the concurrent actuation, moreover, Japanese Unexamined Patent Publication No. 2001-351477 discloses the following structure. That is, in order to restrict an actuation amount the operation knob, a protruding portion is provided at center of the switch body or a movable restricting member is movably supported between the switch body and the operation knob in a horizontal direction (see FIGS. 6 and 7).
In Japanese Utility Model Registration No. 2590446, on the other hand, a malfunction that if a user actuates an operation knob obliquely (oblique actuation), a mirror is turned or is not turned depending on a direction in which the operation knob is actuated is avoided in such a manner that two switch elements are disposed at each of four corners of the operation knob, that is, eight switch elements are provided in total. In a case where the user actuates the operation knob, only when four of the eight switch elements, which are disposed at two sides of a pushed operating part, are closed simultaneously, a switching operation is performed normally.
In Japanese Unexamined Patent Publication No. 2001-351477, the dead short of the circuit, which occurs due to the concurrent actuation, is prevented in view of a mechanism of the switch. Consequently, the switch is complicated in structure and is large in size as a whole. In Japanese Utility Model Registration No. 2590446, moreover, the malfunction due to the oblique actuation of the operation knob can be avoided by the change in arrangement of the switch elements and the change in electric circuit. In the electric circuit, however, no countermeasures are taken against a malfunction due to the concurrent actuation. In order to prevent the malfunction due to the concurrent actuation, a microcomputer may be provided to stop an electric motor upon reception of a signal indicating the concurrent actuation from the switch. However, the provision of the microcomputer has high components cost.